The kids are out of school, and the cows are starting to get hot — summer is here. Having grown up in the Deep South, I know what heat and humidity can do to people and to cows. It's brutal!

After having lived much of my adult life in the higher elevations of the arid West, I have recently moved back to the muggy South. I guess I was spoiled out West because I feel the heat stress of the South now even more. For cows in the South, however, I think it's actually much better than it used to be.

Back in the early days of my career, I worked for a feed company servicing dairy producers in central Texas. I remember frequently seeing many cows with their tongues out and truly looking miserable on hot summer afternoons. During this misery, several metrics went into rapid decline. Among these were milk flow, butterfat, reproductive success, and maybe most importantly, feed intake. As intake dropped, so did my income as a feed guy. This result of heat stress was hard on me and the cows!

We all know the adage that necessity is the mother of invention. Smart people knew back then that for cows to reach their full potential, we needed to cool them better. To a significant degree these many years later, we have been successful in the effort. As I watch the current marketing and other information on the modern world of cow cooling, I look back and smile at how we got here.

Return on investment

Our consulting group has the opportunity to serve a few dairy clients in the area where Louisiana and Mississippi share an east-west border. These cows are in a very different world than much of the work we do out West. Earlier in my career, there were many more of these small dairies in that geography, but most have left the business. These herds had some real advantages for milking cows, including the gifts of a long season for annual ryegrass grazing and very mild winters. The tradeoff, though, was very hot and very humid summers.

Back in the early 1990s, this may well be where some of the more cutting-edge practices of cooling cows were born. I know that there was some very important research going on in academic environments, but that was not to be outdone by what my feed-selling colleagues were doing in the deep and very humid South.

Due to the unfortunate impact of heat stress and reduced feed intake on a feed salesperson’s monthly paycheck, those guys got busy figuring out how to keep cows cool. They knew that cooler cows would eat more, make more milk, maybe get pregnant, and along the way, help with summer feed sales. All these items worked in the favor of everyone involved, and progress was made.

A common sight at those dairies then was a wet brewers grains pit that had a feed line on three sides. Yes, that is correct — free choice wet brewers grains. With what we know now in nutrition science, we might also call it free choice 18:2 fatty acids, the perfect recipe for butterfat depression. It was better than nothing, and the abundance of digestible neutral detergent fiber (NDF) in brewers grains was not a bad fit for the cows. Most of these cows were also on a diet including free choice, long grass hay. It's a reminder that a few pounds of intake from free choice grass hay can cover a multitude of nutritional sins. If it's literally dragging in the cow’s mouth from both sides of the muzzle, it has a lot of impact on the rumen.

Going back to the feed guys, this method of making cows eat during heat stress did not keep the feed company trucks running. Also, cows lost intake of important vitamins, minerals, and various additives as the consumption of the grain mix went down.

The response was that these feed salespeople became experts in cow cooling. I remember they cooperated with local and state extension personnel, fan manufacturing companies, and others. They learned a lot about pressure pumps, filters, droplet size, check valves, and the other details important to putting lots of water on cows. I remember helping my clients out West connect with a feed store in Louisiana to order sprinkler heads with the right droplet size and spray pattern. This was high science, and it worked. Cooler cows ate more feed and had better summers.

Cool and wet

We are all better for this effort now in the summer of 2024. No matter if it is a week or two of intense heat in the upper Midwest or the unending, day after day heat stress of the southern U.S., as an industry, we take better care of cows in the summer than we used to. Just like the feed sales team in Louisiana, this is good for all our pocketbooks. The return on investment of cow cooling is always good.

After this nice walk down memory lane, what are some take home messages or new ideas for this summer? First, are your cows cooled leaving the parlor? This is the easiest place to put water on cows, and it synchronizes well with their hormonal drive for feed intake just after milking. Everything you need can be bought at the local hardware store.

Secondly, are there ample and abundant water troughs between the parlor exit and the feedbunk? And on that note, how clean are your water troughs? Summer is the time to step up the routine of scheduled water trough cleaning.

Bunk line sprinklers are common in some parts of the U.S. If this is too big of a plumbing project, a unique idea is to consider a water tank on a truck. With a little ingenuity and a small pump, you can douse cows that are locked up for breeding later in the morning or in the afternoon. This is effective and not complicated or costly.

Don't forget ration opportunities as well. Consider increasing the dietary cation-anion difference (DCAD) in the diet with more sodium and potassium and perhaps cooling the starch down a little in favor of digestible NDF in feeds like soy hulls or beet pulp.

As for feeding logistics, consider altering the time of primary feeding and pay close attention to secondary fermentation and heating in the bunk. Extra attention to silage face management, push-outs, and careful rotation of wet by-products can help keep the temperature down in the bunk. This will encourage better summer intake. You may look at doing a split shift for the feeding team to allow for later afternoon and early evening feedings. You can also consider an earlier start time in the mornings during the summer.

And there’s more to learn

The keys to success during times of high heat include building a good summer diet, putting water on cows everywhere possible, keeping the air moving, and practicing excellent bunk management. This will always pay off for milk cows, and please don't forget the dry cows. The early research in general cow cooling has led the way to some very exciting and cutting-edge research on cooling dry cows in an effort to improve the milk production potential of the fetus.

We have come a long way in cow cooling, and there is more yet to come. Look for smart soakers to use artificial intelligence and real-time data to cool each cow for maximum impact. This is exciting and will make the valuable bunk line sprinkler a legitimate option for areas with less available water. More to come on that! In summary, wet the cows to the hide, blow them dry, and do it all over again as often as possible. Fall will be here before you know it.